Capacitive Position Sensor Single Sense Electrode Design
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Solution Overview
Problem
Existing 2D capacitive position sensors based on active capacitive sensing techniques require multiple connections between electrodes and circuitry, increasing complexity and cost, while being sensitive to external ground loading and environmental conditions.
Innovation Solution
A 2D position sensor design featuring drive electrodes in both columns and rows and a single sense electrode extending in both directions, allowing for a single sense channel and reduced connections, with a controller to apply drive signals and measure sense signals, enabling precise position determination without a multiplexer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple connections between electrodes and circuitry are used in existing 2D capacitive position sensors, then measurement precision can be maintained, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple electrode functions into a single sense electrode that extends in both x and y directions. This single electrode replaces what would traditionally require multiple separate sense electrodes and associated circuitry, reducing the number of connections while maintaining the ability to detect position disturbances in two dimensions through integrated capacitive sensing
Solution Approach 2:
The single sense electrode performs multiple sensing functions simultaneously - it detects capacitive disturbances along both the x-axis and y-axis directions. This multi-functional electrode design eliminates the need for separate sense electrodes for each direction, reducing circuitry complexity while preserving measurement precision across the entire 2D sensing area
2Measurement precision
If multiple connections between electrodes and circuitry are used in existing 2D capacitive position sensors, then measurement precision can be maintained, but cost increases
Solution Approach 1:
The patent combines multiple electrode functions into a single sense electrode that extends in both x and y directions. This single electrode replaces what would traditionally require multiple separate sense electrodes and associated circuitry, reducing the number of connections while maintaining the ability to detect position disturbances in two dimensions through integrated capacitive sensing
Solution Approach 2:
The patent uses a single sense electrode pattern that effectively 'copies' or replicates the sensing capability across multiple directions and positions. Instead of physically creating multiple separate electrodes, the single electrode design captures capacitive coupling effects from multiple locations, reducing manufacturing steps and material costs while maintaining sensing precision
3Device complexity
If a single sense electrode extending in both directions is used, then device complexity is reduced, but sensitivity to external ground loading may increase
Solution Approach 1:
The controller sequentially applies drive signals to row and column electrodes and monitors the sense electrode for capacitive coupling changes. This active sensing approach with sequential scanning allows the system to distinguish between genuine position disturbances and background noise or ground loading effects, maintaining sensitivity while reducing complexity
Solution Approach 2:
The patent employs periodic application of drive signals to different electrode combinations (rows and columns) and corresponding periodic monitoring of the sense electrode. This time-multiplexed approach allows the single sense electrode to be used with multiple drive electrodes in sequence, reducing the need for simultaneous multiple connections while maintaining measurement accuracy through temporal separation of sensing operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces the number of connections and circuitry complexity, enhancing reliability and cost-effectiveness while minimizing sensitivity to external factors, allowing for precise position detection in a single-layer electrode pattern.
Implementation Method 1
a sense unit for measuring sense signals representing a degree of coupling of the drive signals applied to the row and column electrodes to the sense electrode
Data Source
AI summary
In one embodiment, a sensor includes a substrate; multiple interconnected sense elements arranged in a first direction on a surface of the substrate; and first interconnected drive elements arranged on a surface of the substrate in the first direction. Each respective one of the first interconnected drive elements are located adjacent to and between respective ones of the sense elements to form first sets of sense and drive elements alternating in the first direction. The sensor also includes second interconnected drive elements arranged on a surface of the substrate in a second direction. Each respective one of the second interconnected drive elements are located between respective ones of the sense elements to form second sets of sense and drive elements alternating in the second direction.